I've seen families walk in and the kids pull bikes and cars down off the racks and ride them around the store like it was a playground! It becomes their own personal playspace, and they leave the place trashed for other shoppers and the workers to clean up after them.
I would have lit my kids butts on fire if they ever misbehaved like that in a store, but it seems parental control of their kids is a thing of the past now...
A friend of mine handled kids riding or playing with toys by saying she would get a cart for them to take it to the front for purchase. They stopped immediately! And if the parents were there she would address them in the same way. Parents would stop their kids then.